Ellobiopsidae of Alaskan Coastal Waters

ETHELWYN G. HOFFMAN and ROBERT M. YANCEY!

ABSTRACT: Four species of ellobiopsids were taken in Alaskan coastal waters .Thalassomyces fagei ( a synonym of Amallocystis fagei ) was found to parasitizespecimens of the euphausid Thysanoessa raschii taken in Kachemak Bay, Alaska.The development of T . fagei external to the host from a small knob to the matureform was found to occur by repeated dichotomous branching. T. fagei occurred dur­ing April and May hut was not observed at other times of the year. Thalassomycessp. was found to be parasitic on specimens of the mysid Acanthomysis pseudoma­cropsis taken in Kachemak Bay, Alaska. The range of Thalassomyces capillosus, para­sitic on the caridean Pasiphaea pacifica, is extended from Coos Bay, Oregon, to OrcaBay, Prince William Sound, Alaska. Ellobiopsis chattoni was found to parasitizethe copepod Metridia longa, a new host of this ellobiopsid. Specimens of E. chattoniwere taken in the waters of southeastern Alaska, extending the range of E. chattonifrom the Atlantic to the north Pacific.

THE SYSTEMATIC POSITION of the family Ello­biopsidae Coutiere and the genera therein hasbeen an enigma since their original description.According to Margaret ]epps (1937), T. Scottin 1897 first described the ellobiopsid nowknown as Ellobiopsis chattoni as a "? infusorianparasite" of the copepod Calanus finmarchicu s.She state's also that in 1910 Caullery associatedthe ellobiopsids with the Dinoflagellata. Variousauthors have continued to consider these or­ganisms to be closely related to the dinoflagel­lates. ]epps points out that a relation with thefungi is possible. Boschma ( 1949, 1956, and1959) reviewed the entire group and preferredto consider them as "Protista of uncertain posi­tion." He noted that the ellobiopsids have af­finities with the following groups: parasiticperidinians, flagellates, and possibly fungi of thefamily Saprolegniaceae, and that the group ismade up of a number of heterogeneous elements .

The family Ellobiopsidae is a rather hetero­geneous group consisting of several genera.Members of the genus Ellobio cystis are epi­bionts, whereas members of the genera Ellobi­opsis and Thalassomyces are parasites. This studyis concerned only with the last two genera .

I U. S. Bureau of Commercial Fisher ies BiologicalLaboratory, Auke Bay, Alaska. Manuscript receivedAugust 20, 1964 .

70

Various pelagic crustaceans, including copepods,euphausids, and carideans, are hosts of species ofEllobiopsis and Thalasso myc es.

Organisms of the genus Ellobiopsis parasitizeseveral species of copepods . Various species ofCalanus have been reported by Marshall et aI.(1934), Marsha ll and Orr- (1955), and ]epps(1937) to be parasitized by Ellobiopsis chattoni.Pseudocalanus (Marshall, 1949), Clausocalanus(Hovasse, 1951), Acartia (Boschma, 1956), andMetridia, in this work , have also been found ashosts of E. chattoni.

]epps (1937) described very early forms ofthis parasi te which she found on the antennaeand mouth parts of Calanus finmarchicus. Thesefirst appeared as small knobs on the setae of themouth parts. At maturity E. chattoni consists ofa pear-shaped part, the trophomere, which isattached by a stalk to the host's appendage. Dis­tal to the trophomere there may develop one ortwo rounded segments, the gonomeres, in whichsporulation takes place. According to jepp's de­scription of sporulation in E. chattoni, smallbuds arise on the free surface of the gonomere,each of which undergoes a series of fissions,forming spores. The mechanism of spore releaseand the relation between free spores and the oc­currence of small knobs on the host appendagesis unknown.

Ellobiopsidae of Alaskan Coastal Waters-HOFFMAN and YANCEY 71

Species of Thalassom yces (formerly known asAmallocystis ) are different in many respectsfrom those of Ellobiopsis . Each T halassomycesconsists of a tuft of trophomeres extending froma central stalk, whereas each Ellobiopsis has onlyone trophomere. The number of trophomeresextending from the stalk is used as a species­differentiating character in Thalassomyces.

The gonomere (or gonomeres) which formson the distal end of the trophomere is separatedby a septum from the trophomere. Individualsof Ellobiopsis species have one or two gono­meres. If more than one gonomere is present, asin the Thalassom yces species and some Ello­biopsis species, each is separated from the nextby a septum. Sporulation has not been describedfor any Thalassomyces species but is assumed to

occur. Old individuals of Thalassomyces spp.may be found with numerous empty gonomeres;some with collapsed walls may remain attachedto the trophomere.

Various euphausids, mysids, and carideanshave been reported as hosts for Thalassomycesspecies. The ellobiopsid may be attached ven­trally to the host 's abdomen, as in T . racem osus,to the dorsal surface of the carapace, as in T.fagei and Thalassomyces sp., or at the base of therostrum, as in T . c;apillosus ( Boschma, 1956 ) .

As a result of this study the ranges for threespecies of ellobiopsids have been extended to

Alaskan waters. They are T . fagei, T. capillosus,and E. chattoni. T . capillosus is the only speciesof the three prev iously recorded in the northPacific Ocean. The development of T . fagei isdescribed, and seasonal distribution of this spe­cies is discussed. Metridia longa was found to bea host for E. chattoni.

OBSERVATIONS AND DISCUSSION

Thalassomyces fagei

The genus was named Amallocystis unti l1959, when Boschma pointed out that , becauseof its pr iority, Thalassomyces is the valid name.

The euphausid Thysanoessa raschii (M. Sars)has been recorded as host for this ellobiopsid ontwo previous occasions. Einarsson ( 1945) de­scribed Amallocystis sp. parasitic on T . raschiitaken in May in Faxafloi to the west of Iceland.

Boschma (1949 ) established that the Amallo­cystis sp. of Einarsson was A . fagei (Boschma),and later (1959 ) he corrected the generic nameto Thalassom yces. Glover ( 1952) observed twospecimens of this euphausid infected with T.fagei. One was taken in Ju ly and the second inAugust of 1948 in the region of May Island inthe Firth of Forth. Initially T . fagei (Boschma)was described as an Antarctic species, but itsdistribution has been extended to include thenorthern Atlantic waters by reports of Einarsson(1945), Glover (1952 ), and Macdonald (1927).Macdonald reported the occurrence of Staph­locystis racemosus on the euphausid Meganyc­tiphanes norvegica taken in the Clyde Sea.Boschma (1949) believes that this ellobiopsidwas T . fagei and not S. racemosus.

In our investigation we also found T. fageiparasitic on Thysanoessa raschii. The specimenswere taken during the spring of 1963 in threesmall inlets which are part of Kachemak Bay,Alaska ( 59°27'N, 151°33'W ) . The sampleswere taken in 20-minure oblique hauls of a Y2 -mplankton net with a standard No . 2 mesh. Thedepth in the area did not exceed 53 fathoms.Th is is the first record of this species of ello­biopsid from the Pacific Ocean, and its range isthus extended from the Atlantic to the north­eastern Pacific.

The ellobiopsid parasites are attached to thehost by a stalk which extends through the dorsalside of the carapace and penetrates the tissuesbelow. The parasite is located in a dorsal con­cavity on the carapace of the host which is notfound in uninfected euphausids ( Fig. 1) . Aninfected T. raschii usually bears only one Tbalas:somy ces, although up to four were observed. Aspecimen bearing two parasites is shown inFigure 2.

The mature parasite has 30-50 trophomereswhich are ramifications of the single centralstalk. The trop homeres are expanded distallyinto a club shape. Trophomeres with one to sixgonomeres were observed, although more com­monly three to five occur. The gonomeres arespherical to slightly elliptical in shape. Figures3 and 4f are a photograph and a camera lucidadrawing respectively of a mature parasite. Inolder individuals some of the distal gonomeresare empty. The gonomere remnant may break

72 PACIFIC SCIENCE, Vol. XX, January 1966

FIG. 1. A young ellobiopsid located in a concavity on the dorsal side of host's carapace.

off, leaving a small tuft, or the walls may col­lapse, producing a filament hanging from theend of a more proximal gonomere (Fig. 4f).Jepps (1937) has observed that in Ellobiopsischatt oni, parasitic on Calanus finmarchicus, thiscondition of the gonomere is the result ofsporulation. She noted that when all the sporeshave been released, the test of the distal segmenteither degener ates or is left full of debris .

The development of Thalassomyces jagei was, worked ' out from a sequence of specimens taken

iIi various stages of growth (Fig. 4). The ello­biopsid was removed from its host and placedwith the stalk extending upward to facilitatedrawing. The illustrations show this aspect ofthe parasite, except Figures 4a and 4b, which areviews from one side. All the drawings were donewith the aid of a camera lucida.

It is not known whether the initial infectionby the parasite is located internally or externally.Jepps (1937) hypothesized that E. chattoniinitially penetrates the host from the outside. Inthe material of Thysanoessa raschii examined inthe present study, Thalassomyces jagei wasfound to have a well-established internal struc­ture at the earliest stages in its extern al develop­ment. Figure 4b is a lateral view of T. jageishown extending through the host carapace. Thestructure in the lower left is the "sieve plate" ofBoschma ( 1949 ) . Numerous protoplasmic ex­crescences protrude through openings in thecuticle of the ellobiopsid. These excrescences arethought to be the organ of absorption of foodfor the parasite.

The major function of the extern al structureof the parasite is assumed to be reproductive.

FIG. 2. Euphausid with two discrete parasites.

Ellobiopsidae of Alaskan Coastal W aters-HOFFMAN and YANCEY 73

Whether reproduction is sexual or asexual isunknown. These observations agree with the hy­pothesis accepted by Boschma ( 1949) for T.fagei concerning the assumed release of sporesfrom the gonomere. Jepps (1 937) describedsporulation in the distal structure which shetermed the gonomere of Ellobiopsis chattoni.Hovasse ( 1951) observed sporulation of E.fagei. No observations of sporulation in a Thal­assornyces species are available.

The extern al development of T . fagei is initi­ated by a small knob-shaped structure appear­ing thro ugh the middorsal region of the carapaceof the host. This single knob bifurc ates slightly ,producing a bilateral structure ( Fig. 4a) . Thenext stage appears to be the result of simul­taneous bifurcation of each of the previouslyformed lobes, resulting in a four -lobed struc­ture ( Fig. 4c) . Furth er development ofT. fageiis accomplished by repeated simultaneous dicho­romous branching of each of the existing lobes.The simultaneous nature of the bifurcation isretained unti l the fifth or sixth division at whichtime the branching appears to get out of phase.

In this study 77 specimens of T. fagei wereexamined. These were taken in plankton samplesfrom three stations located in the Cook Inletarea of Alaska. The locations of the stations wereas follows: at the mouth of Kasitsna Bay (59°28.7'N, 151°3 3'W ) and two stations in Tutka

Bay (59°26.5'N, 151 °22.7'W, and 59°25 .5'N,151°19.5'W ) .

The seasonal distribution of T. fagei wasfound to coincide in part with that reported forthe same species parasitic on Thysanoessa iner­mis by Einarsson ( 1945) . He found T halas­somyces fagei (as Amallocystis sp.) on matureeuphausids duri ng May only. In our work dur­ing February and March of 1963 numerousThysanoessa raschii were observed, but most ofthe individuals taken during this time werejuveniles. Early stages of T halassom yces fageifirst appeared on the host early in Apr il, 1963.Mature ellobiopsids were taken from late Apri luntil about the first of June. The external struc­tures of T . fagei were not present on the euphau­sids taken in February or March , nor were theypresent late in June. During May, 1963 we noted13% average infection of Thysanoessa raschiiby Thalassom yces fagei. This was based on threesamples containing 239 specimens of Tbysano­essa raschii, of which 33 were parasitized.

It appears unlikely, at least from the preservedmaterial, that a mature Thalassom yces fageicould pass through the hole in the carapace ofthe host at molting. Th is is due to the fact thatthe host's exoskeleton closely surrounds the stalkof the ellobiopsid. Since euphausids have a highintrinsic rate of molting, one can assume eitherthat the euphausids cont inue to molt with their

FIG. 3. Euphausid with a mature parasite.

74 PACIFIC SCIENCE, Vol. XX, January 1966

I I , I200A

, I , I

200~

, I I I

200/'1

a

c

e

Stalk __~\

b

d

f

! I I I200-""

, I I I200~

~

200..,M

FIG . 4. D rawings illus trating the developmental stages of Tbalassom yces [agei.

Ellobiopsidae of Alaskan Coastal Waters-HOFFMAN and YANCEY 75

usual frequency or that the parasite interfereswith the regulation of molting. In the formercase, the external development of T. fagei dur­ing the intermolt would of necessity be ex­tremely rapid. If the latter is true, as is the casewith the rhizocephalans, molting would be heldin abeyance while the external development andassumed reproduction of T . fagei take place.

In order to resolve this question and others,work on the internal development needs to beundertaken. Most studies on ellobiopsids, includ­ing this one, have dealt with the external aspectsof these parasites only, while in reality it is theinternal aspects which will reveal their biologicalstatu s.

The observations on the effect of Thalas­som yces fagei on Thysanoessa raschii agree withthe reports of Einarsson ( 1945) on the effectsof T. fagei on Thysanoessa inermis. Einarssonstated that T . fagei probably castrates the animalit attacks. None of the parasitized Thysanoessaraschii examined in this study had either themale anrennal armature or the first pleopods de­veloped as copulatory organs; in the case offemales no sign of a thelycum was evident.Einarsson (1945 ) showed that parasitized ma­ture females had completely disorganized ovariesthrough which ramifications of the stalk of theparasite extended.

Boschma (1949) sectioned parasitized eu­phau sids and found that the ellobiopsid did notdisorganize the host 's ovary, although the pro­toplasmic excrescences which protrude throughholes in the sieve plate extended throughout theorgan. The ovary was not degenerated, althoughBoschma found that all the eggs present weresmall.

The most complete works on the genus Thal­assom yces are those by Boschma (1949 and1959 ) , which contain a comprehensive reviewof the literature as well as descriptions of thespecies.

On the basis of these and other observa­tions concerning the biology of ellobiopsids,a number of conclusions and hypotheses canbe drawn concerning members of the genusT halassomyces.

1. The development of the structures externalto the euphausid and the similarity of these toreproductive structures of Ellobiopsis strongly

suggest that they are primarily reproductive.These external structures follow the establish­ment of a large internal body thought to be ofa vegetative nature. The length of "life" of theinternal portion of the parasite and its seasonalpresence are unknown. Therefore the true per­centage infection cannot be determined on thebasis of the external structures alone.

2. The external reproductive structures of T.fagei appear in early summer in Alaska, whereasthey appear in midsummer in the Atlantic. Theduration of this manifestation of individualellobiopsids is unknown.

3. Our observations in this study and those ofEinarsson and Boschma on the sexual develop­ment of euphausids support the interpretationthat T. fagei suppresses the sexual developmentof the host . Also the ellobiopsid may interferewith the endocrine control of molting, at leastduring its period of external development.

4. Further understanding of the biologicaleffects of these parasites on planktonic crusta­ceans will be achieved only by laboratory in­vestigations on the internal development of theparasite and on the nature and fate of the bodiesproduced in the gonomere.

Thalassomyces sp.

Six specimens of Thalassom yces sp. werefound to parasitize the mysid Acanthomysispseadomacropsis. The ellobiopsid is generallylocated on the dorsal surface of the carapace ofthe mysid. In each case the mysid was para­sitized by two ellobiopsids. In one instance, oneof the ellobiopsids was located on the carapace,and the other was on the dorsal surface of thesixth abdominal segment of the mysid. Themature Thalassomyces specimens were taken inplankton samples from stations in the KachemakBay area of Alaska (59°27'N, 151°33'W) inOctober and December, 1963 and in February,1964.

The mature parasite has 7-20 short-stalkedtrophomeres which are ramifications of thesingle central stalk. The trophomeres average0.75 mm long, although this feature is variable.The usual number of gonomeres present on eachtrophomere is three, and no more than this nurn-

76

ber have been observed. The transverse diameterof the gonomeres ranges from 0.14 to 0.21 mm,the average being 0.17 mm.

The species identification of these specimenshas not been determined. This ellobiopsid maybe T . fagei, although there are differences in anumber of external features of Thalassomycessp. from the specimens of T . fagei parasitic onthe euphausid Thysanoessa raschii taken in thesame area. The number of trophomeres, thelength of the trophomere stalk, and the numberof gonomeres vary from the previ ously men­tioned species. Boschma ( 1959) pointed outthat a number of variations of this type occuramong T . fagei individuals parasitic on differentspecies of euphausids. The location of the ello­biopsid on the carapace tends to support thehypothesis that this is T. fagei, while the factthat th is species parasitizes a mysid rather thana euphausid may be sufficient to propose this asa new species, inasmuch as T . fagei has onlyeuphausid hosts. The only Thalassomyces speciesreponed to parasitize a mysid is T. fasciatus.Th is ellobiopsid is located on the ventr al side ofthe first abdominal segment of its host.

Until more material is available and can beexamined by an authority, it is advisable to con­sider this ellobiopsid as Thalassomyces sp.

T halassomyces capillosus

The first report of ellobiopsids from thenorthern and eastern Pacific was that of Me­Cauley (1962) . He found T halassomyces capil­losus ( Fage), formerly known as Amallocystiscapill osus, on a specimen of Pasiphaea pacificaRathbun, a pelagic shrimp taken 15 miles westof Coos Bay, Oregon (43°20A'N , 124°45.8' W )in a midwater trawl. McCauley ( 1962) stated,"This work adds P. pacifica as a host and extendsthe known range of this parasite to the north­eastern Pacific." According to McCauley, T.capillosus had previously been described as para­sitic on several species of pasiphaeid shrimp,most of which were taken in the north Atlantic.

Five Pasiphaea pacifica taken by the Explora­tory Fishing and Gear Research Base of theBureau of Commercial Fisheries, Juneau, Alaska,were examined for ellobiopsids. A single speci-

PACIFIC SCIENCE, Vol. XX , January 1966

men of P. pacifica taken by a shrimp trawl atstation No. 427 located in Orca Bay, Prince Wil­liam Sound, Alaska (60034'N, 146 °0 1'W) wasparasit ized. This individual was taken betweendepths of 74 and 120 fathoms on September 9,1962, by Rathjen (1963). In addition, a singlespecimen taken in Lynn Canal in southeasternAlaska ( 58°51.2' N , 135°15.5'W) was para­sitized by T . capillosus. This pasiphaeid wastaken May 14, 1964, by an Isaac-Kidd rnidwarertrawl at a depth of 59.6 fathoms .

The ellobiopsid is located dorsal to the eyes ofthe host at the base of the rostrum. On one speci­men there were approximately 40- 50 rropho­meres on either side of the rostrum; on the otherspecimen there were 50-60. This estimation ofthe number of trophomeres on the first may notbe accurate because the specimen was in poor

. condi tion. Distal to the trophomere of the para­site is one or, more commonly , two gonomeres.The terminal gonomere is ovoid, almost twice aslong as broad. When two gonomeres are present,the proximal one is somewhat rectangular be­cause of the septa which separa te it from themore distal gonomere and from the trophomere.

The morphology of the parasite, its size andlocation on the host, and the host species agreefor the most part with the description of T . cap­illosus (Fage ) . The only discrepancy was thatrather than a single gonomere there were almostalways two gonomeres on each trophomere.

Effects of T. capillosus on the carapace ofP. pacifica similar to those found by McCauleywere noted. Th e rostrum is distorted and pro jectsalmost dorsad rather than anteriad. On eitherside of the base of the rostrum is a swelling notfound in unparasitized P. pacifica. A dumbbell­shaped opening in the carapace extends betweenthe two swellings. A tuft of trophomeres ofT . capillosus extends from the tissue of the hostthrough both of the expanded ends of the slit.Figure 5 is a camera lucida drawing illustratingthe rostrum of a parasitized P. pacifica.

This study extends the known range of T.capillosus as a parasite on Pasiphaea pacificafrom off the Oregon coast (McCauley, 1962) tothe Prince William Sound area of Alaska. It isexpected that further observations will fill inthe range and possibly extend it still farther.

Ellobiopsis chattani

The genus Ellobiopsis contains two species,E. fagei Hovasse and E. chattani Caullery. E.[agei was described as parasitic on the cope­pod Clausacalanus arcaicornis Dana by H.o:,asse(195 1 ) . E. chattani is known to be parasltlc. onthe following copepods: Calanus finmarchtcus(Marshall er al., 1934; Marshall and Orr, 1955;Jepps, 1937) ; Calanus helgalandicus (Boschma,1949); Pseudacalanus minutus (Marshall, 1949) ;and A cartia clattSii (Boschma, 1956). Marshallet al. and Marshall and Orr state that E. chattaniis more common on Calanus during the summerthan the winter.

In our investigation Metr idia langa was foundto be a host for Ellobiopsis chatt ani. This is thefirst record of a species of Metridia as host forellobiopsids. M. lucens, which was present inthe same samples, was not found to be para­sitized by E. chattani. Parasites were observedonly on Stage V males and females. M. langawas the only copepod taken which was host toa species of ellobiopsid.

The plankton samples examined during thisstudy were taken in southeastern Alaska at themouth of Auke Bay (58 °21'N , 134°4 1'W) bythe Oceanography Investigation of the Bureauof Commercial Fisheries Biological Laboratory,Auke Bay, Alaska. Th e samples were takenmonthly during 1962 and 1963. Samples w.e~e

taken both dur ing the day and at night. Metrt dtalanga and M. lucens were the most abund~nt

copepods in the Auke Bay samples taken during

Ellobiopsidae of Alaskan Coastal W aters-HOFFMAN and YANCEY 77

the late fall in both 1962 and 1963. Throughoutthe other seasons Metridia are taken in con­siderably fewer numbers. At night both speciesof Metridia are common in the sample taken justbeneath the surface, whereas in the daytimeMetridia are most common in the samples takenfrom approximately 20 m. Few Metridia weretaken in the samples from Kasitsna Bay, Alaska,and none of these were parasitized by E. chat­toni.

E. chattani was most abundant in the samplesfrom Auke Bay taken in October and N ovemberof 1962 and 1963. The percentage of infectionwas established by examining 250 specimens ofMetridia and calculat ing the percentage of in­fection in this subsample. Samples taken in themiddle of Nov ember , 1962 showed the highestinfect ion rate. The percentage of infected cope­pods ranged from 7.7% in the daytime samplesto 22.4% in the nighttime samples taken at thesame station. N o explanation of this differenceis available. During October and N ovember,1963 approximately 5% of the Metridia speci:mens were found to be parasitized by E. chattam.

The morphology and development of E. chat­toni is described and discussed by Jepps (193 7) .Our observations of E. chattani on Metridiaagree with those reporred by Jepps on its para­sitizing Calanus finmarchicus. An ellobiopsid in­dividual initially appears as a small knobl ikestructure on one of the setae of any of thecephalic appendages. The mature individuals areattached by a stalk which extends into the tissueof the host's appendage. There are one or twogonomeres present on the mature ellobiopsid.The distal gonomere sometimes has an "apicalcone" as described by Jepps. Alth ough severalimmature E. chattani may be located on a singlehost, no more than three mature parasites wereobserved on any single specimen of M. langa.

The finding of Ellobiopsis chattani on Metri­dia langa in the coastal waters of southeasternAlaska extends the known range of this parasitefrom the norrhern Atlantic Ocean to the north­eastern Pacific Ocean. Thi s is the first report ofE. chattani taken in the Pacific.

,I I200.,M

F IG. 5. Drawing show ing the anterior portion ofthe carapace of an inf ected Pasiphaea pacifica.

ACKNOWLEDGMENTS

The authors would like to thank the follow­ing individuals whose work has aided this study:

78

Mr. Roland McBride, who maintains the Bu­reau of Commercial Fisheries Kasitsna Bay Shell­fish Laboratory and is in charge of carrying outthe year-round plankton sampling program; Mr.Jerrold Olson, who took the photographs; Mr.Gerald Reid, project leader for the zooplanktoninvestigation being carried out in Auke Bay, andwho allowed the use of the plankton samplestaken in that area; and Miss Gail Heron andMr. Dave Damkaer of the University of Wash­ington Department of Oceanography, who veri­fied the identification of the copepods.

REFERENCES

BOSCHMA, H. 1949. Ellobiopsidae. DiscoveryRept.25 :283-314.

--- 1956. Ellobiopsidae. Conseil Perm. In­tern. Explor. Mer. Zooplancton Sheet 65: 1-4.

--- 1959. Ellobiopsidae from tropical WestAfrica. Arlanride Rept. 5:145-175.

EINARSSON, H. 1945. Euphausiacea, 1. North­ern Atlantic species. The Carlsberg Founda­tion 's Oceanographical Expedition Round theWorld, 1928-30, and Previous "Dana" Ex-

.. peditions. Dana Rept. 5(27) :1-185.

GLOVER, R. S. 1952. Continuous plankton rec­ords : The Euphausiacea of the northeasternAtlantic and the North Sea, 1946-1948. HullBull. Marine Ecol, 3(23):185-214.

PACIFIC SCIENCE, Vol. XX , January 1966

HOVASSE, R. 1951. Contributions a la connais­sance biologique des Ellobiopsidae ; la sporu­lation chez Ellobiopsis jagei sp. nov. C. R.Acad. Sci. Paris 233 :980-982.

JEPPS, MARGARET W. 1937. On the protozoanparasites of Calanus finmarchicus in the ClydeSea area. Quart. J. Microscop. Sci., New Series316,79(4) :589-658.

MACDONALD, R. 1927. Food and habits of Meg­anyctiphanes norv egica. J . Marine BioI. Assoc.U. K. 14 (3 ) :753- 784.

MARSHALL, S. M. 1949. On the biology of thesmall copepods in Loch Striven. J. MarineBioI. Assoc. U. K. 28 (l ) :4 5- 122.

MARSHALL, S. M., A. G. NICHOLLS, and A. P.ORR. 1934. On the biology of Calanus fin­marchicus, V. Seasonal distribution, size,weight, and chemical composition in LochStriven in 1933, and their relation to thephytoplankton. J. Marine Biol. Assoc. U. K.19 ( 2 ) :793-828.

MARSHALL, S. M., and A. P. ORR. 1955. TheBiology of a Marine Copepod, Calanus fin­marchicus (Gunnerus). Oliver and Boyd, Ed­inburgh. 188 pp.

MCCAULEY, J . E. 1962. Ellobiopsidae from thePacific. Science 137 ( 3532 ) :867-868.

RATHJEN, W. 1963. Fishing ; Log M/V "Ya­quina ," Shrimp Explorations, Gulf of Alaska,1962-1963. Exploratory Fishing and GearResearch Base, Bureau of Commercial Fish­eries, Juneau, Alaska. 29 pp .